The present invention relates to a complex rare-earths doped optical waveguide. In particular, the complex rare-earths doped optical waveguide in accordance with an embodiment of the present invention is for modifying emission spectrum of erbium that is able to significantly enhance optical gain from shorter wavelength than 1530 nm.
Wavelength division multiplexing method has been studied as a core technology for satisfying increasing demand in the area of optical communication networks. Likewise, optical amplifiers with broadband gain are needed.
Currently, gain wavelength of erbium doped silica optical amplifier is fixed over 1530 nm. Also, in order to amplify other wavelength regions, optical gain is obtained at xcx9c1300 nm, xcx9c1470 nm, and xcx9c1650 nm by employing praseodymium (Pr) ion and thulium (Tm) ion, respectively.
Erbium ion is an efficient gain medium. Since erbium results in a conspicuous gain when configured to optical fiber amplifiers regardless of host compositions of the optical fibers, many studies have been performed to obtain gain at shorter wavelength than 1530 nm by employing erbium ion.
When erbium ion dopes a crystal or a glass, it is excited by light or electricity and as a result, fluorescent emission in 1460xcx9c1650 nm is evident, which is from 4I13/2xe2x86x924I15/2 transition.
Gain wavelength of conventional erbium doped optical fiber amplifiers is between 1530 nm and 1600 nm and it is difficult for conventional erbium doped optical fiber amplifiers to obtain gain at wavelength shorter than 1530 nm. It is because that the emission cross-section of 4I13/2xe2x86x924I15/2 transition is small at wavelength shorter than 1530 nm.
Generally, spectral lineshape of a gain spectrum is similar to shape of the amplified spontaneous emission spectrum, it is difficult for conventional erbium doped optical fiber amplifiers to obtain gain at wavelength shorter than 1530 nm.
A complex rare-earths doped optical waveguide is provided. The complex rare-earths doped optical waveguide in accordance with an embodiment of the present invention includes clad and core. The core is doped with erbium (Er) ion. The interior or exterior region of the core is doped with at least one of complex rare-earth ions. The interior and (or) the exterior region of the core, where the rare-earth ion (s) dope (s), is at a certain distance apart from the erbium-doped region.
Preferably, the complex rare-earth ion is thulium (Tm), terbium (Tb), dysprosium (Dy), or neodymium (Nd).
Preferably, erbium (Er) is doped within certain length from center of the core.
Preferably, the interior and (or) exterior of the core is doped with at least one complex rare-earth ion.
Preferably, a layer doped with at least one complex rare-earth ion wraps the erbium-doped layer of the core.
Preferably, distance between the erbium doped layer and the complex rare-earths doped layer is farther than 20 nm.
A complex rare-earths doped optical waveguide is provided. The. complex rare-earths doped optical waveguide in accordance with an embodiment of the present invention includes clad and core. In the whole region or in a fraction of the core are doped combination of erbium (Er) ion and ytterbium (Yb) ion. A layer, a certain distance apart from the erbium/ytterbium-doped layer is introduced and the layer is doped with at least one complex rare-earth ion.
Preferably, the complex rare-earth ion is thulium (Tm), terbium (Tb), dysprosium (Dy), or neodymium (Nd).
Preferably, erbium (Er) and ytterbium (Yb) are codoped in the core.
Preferably, the internal or the surface of the core is doped with at least one complex rare-earths ion.
Preferably, the internal or the surface of the core is wrapped by at least one complex rare-earths ion.
Preferably, distance between the erbium (Er) and ytterbium (Yb) codoped layer and the complex rare-earths doped layer is farther than 20 nm.
A complex rare-earths doped optical waveguide is provided. The complex rare-earths doped optical waveguide in accordance with an embodiment of the present invention includes clad and core. The core is doped with erbium (Er) ion and part of the clad is doped with at least one complex rare-earths ion.
Preferably, the complex rare-earths ion is thulium (Tm), terbium (Tb), dysprosium (Dy), or neodymium (Nd).
A complex rare-earths doped optical waveguide is provided. The complex rare-earths doped optical waveguide in accordance with an embodiment of the present invention includes clad and core. The core is doped with combination of erbium (Er) ion and ytterbium (Yb) ion and part of the clad is doped with at least one complex rare-earths ion. A complex rare-earths doped layer is introduced apart a certain distance from the core, in the clad region.
Preferably, the complex rare-earths ion is thulium (Tm), terbium (Tb), dysprosium (Dy), or neodymium (Nd).